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Author Topic: Guy Wire Insulators.....Yes or No?  (Read 1081 times)
NZ4Z
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« on: February 22, 2008, 10:39:51 PM »

I am erecting 60 ft of Rohn 25G, and will guy at 30 & 60 feet, on 3/16 wire. Some say put it up without insulators, and then if you have a problem, add them. They say it's a hassle, and not to worry about them unil the interference happens.

Thanks as Always

73

Steve
NZ4Z
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N6AJR
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« Reply #1 on: February 22, 2008, 11:09:05 PM »

I usually add them every 7 feet or so.. it helps
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KZ1X
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« Reply #2 on: February 23, 2008, 01:54:47 AM »

Guy the tower with Phillystran and your problems are over.

There's no point to putting up a tower and getting a nice beam, and then having the pattern wrecked by re-radiating guy lines.
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W5FYI
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« Reply #3 on: February 23, 2008, 05:04:30 AM »

In theory, resonant guy lines can be a problem, but in practice they seldom are. In a published report several years back, a study showed they had only insignificant effect on radiation or antenna resonance. IIRC, the only affect on a yagi antenna was a change in its SWR when it was aimed through an adjacent tower's resonant guy wire. So, if you have more than one tower, and your antenna is on the lower tower, you might want to break the taller tower's guys with insulators. Otherwise, it's probably unnecessary hassle and overkill.

Stew, W5FYI
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AA4PB
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« Reply #4 on: February 23, 2008, 06:23:37 AM »

Phillystran makes the most sense. Then there is zero concern about guy interferrence.
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W5CPT
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« Reply #5 on: February 23, 2008, 07:41:24 AM »

I also will recommend Phillystran. If you are concerned about Guy Resonance, Phillystran is the answer. Sit down with a pad, pencil and calculator and figure the cost both ways. The Philly will be a bit more $, BUT (that's a BIG but) the work involved is tremendously different. Four to six Guy clamps per insulator, or Grips and the insulators themselves quickly add to the cost of EHS Guys not to mention the work and time (and cut and bruised fingers) make the extra $ worth it.  Many will recommend EHS at the bottom of the Philly Guys for the possibilities of vandalism or fire but that is on a case-by-case basis. Elevated Guy points take care of some of those worries.

If I ever had a Guyed tower, there would be no EHS on it.

My opinion and worth what you paid for it...

Clint - W5CPT
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K6AER
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« Reply #6 on: February 23, 2008, 12:07:31 PM »

Let me mirror what Stew had said. I have my Rohn 25 guyed at 105 feet in three sections and have never noticed any interaction with my SteppIR 4 element beam on top. The patterns are true with extremely low VSWR and the front to back is better than 30 dB.

Now if you plan to use the tower as a vertical radiator in 80 or 160 you will need to insulate the guys but as many have said, Phillystran is the way to go. If you do use Phillystran and you have a danger of fire at the ground guy points you will want to use galvanized guy for the first 20 feet then run Phillystran the rest of the way to the tower. Phillystran will burn and if the outside coating is burned the Kevlar fiber inside will loose its strength.  Big grips will attach to Phillystran just as it attaches to the 3/16 guy.
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KB9CRY
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« Reply #7 on: February 23, 2008, 05:19:26 PM »

Polygon is cheaper and non-conductive also.
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K9KJM
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« Reply #8 on: February 23, 2008, 11:37:48 PM »

I agree that Phillystran is the best way to go, HOWEVER you will still want to use some EHS galvanized steel guy wire in the lower portions of the guys, Down near the ground for safety.  (Grass fire, Kids with knives, etc. While Phillystran is a very strong product, It is very vulnerable to knives, Fire, etc.)
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W8JI
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« Reply #9 on: February 24, 2008, 03:57:06 AM »

The answers are totally subjective because they are based on a single observation of something that might not even mean much. It is very clearly false to claim they NEVER interact.

The fact is guy lines below an antenna **can** interact severely with an antenna mounted near or above them. I can show models where guylines 70 feet below a 40 meter yagi substantially change the 40M Yagi's pattern.

How much they actually interact depends on how long they are, how tall the tower is, the particular antenna being used, and the operating frequency.

A second issue is lightning. If a guyline comes near the house you might wish it had substantial insulation if the tower ever gets hit!

A third issue is if you DON'T break the guylines up you will likely be in really big problems if you want to add a few dipoles lower on the tower. A dipole on the tower will couple substantially more into the guylines than a Yagi at the top will.

A fourth issue is you can never shunt feed the tower if the guylines are not insulated.

A fifth issue is they affect any other antennas within a half wave or more, especially ground mounted verticals, that you might want to use.

I always either use fiberglass guyline or insulators set to isolate the tower. I would never even consider taking a chance based on pure dumb luck or happy "feelings".

73 Tom


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W8JI
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« Reply #10 on: February 24, 2008, 04:05:10 AM »

By the way, there is a pattern that we should all remember.

If we DO observe a variation in SWR it almost certainly means there is a substantial pattern change.

If we DON'T observe a SWR change as we vary something in a system it does NOT mean the pattern or performance does not change.

This applies to many things in other areas too. Because in one narrow case or even a dozen random cases we don't see a certain thing change, it never means in all cases other things don't substantially change. This is why we should be careful making all encompassing statements like "it never affects the antenna" when there are a dozen variables at work.
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K6AER
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« Reply #11 on: February 24, 2008, 10:00:09 PM »

Something Tom had mentioned about guy wires and lightning near the house. Always ground each guy wire station along with the tower.  Wither it is near a house our not.
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W8ATA
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« Reply #12 on: February 25, 2008, 04:57:59 AM »

I am a city lot, single tower guy. I went with Phillystran for the reasons already mentioned such as strength and it being electrically transparent with no insulators to install. That project was just for my tri-bander. What has evolved is a mini antenna farm centered around the tower with dipoles off fiberglass poles out of the tower, two slopers from the tower, and various VHF and UHF antennas. All this was done without having to be concerned with guy lines interacting with antennas and in one case with a dipole almost touching a Phillystran guy. Now maybe some of those antennas are interacting, but it's minimal and I have to live with it. Phillystran has a good website and Texas Towers and Burghardt have good info on it. It was easy to work with even for my old arthritic hands.

Russ
W8ATA
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